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Distinct roles of Chk and Csk in regulation of Src family kinases in hematopoietic cells

Chk 和 Csk 在造血细胞 Src 家族激酶调节中的不同作用

基本信息

批准号：
09671124
负责人：
YAMAGUCHI Naoto
金额：
$ 1.98万
依托单位：
Kumamoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09671124/
关键词：
CD36 cell spreading Csk homologous kinase (Chk)fibronectin integrin VLA5 platelet Src family kinase Lyn thrombin Csk Src型チロシンキナーゼ Lyn インテグリン VLA5 細胞接着 Csk homologous kinase (Chk)translocation チロシンリン酸化

项目摘要

Src family protein-tyrosine kinases play crucial roles in regulating proliferation and differentiation of multiple cell types including hematopoietic cells. The activity of Src family kinases is tightly regulated by tyrosine phosphorylation and dephosphorylation events. The C-terminal Src kinase (Csk), which is expressed ubiquitously, has been shown to phosphorylate the C-terminal negative regulatory tyrosine residue of Src family kinases and suppress their kinase activity. A second member of the Csk family expressed in hematopoietic cells was recently identified as the Csk homologous kinase (Chk).To understand the significance of co-expression of Chk and Csk in hematopoietic cells, we examined the subcellular localization of each protein. Chk but not Csk was localized close to CD36 (membrane glycoprotein IV)-anchored Lyn, and the kinase activity of Lyn was selectively suppressed. Upon stimulation with thrombin, the rapid and complete translocation of Chk away from CD36-anchored Lyn ca … More used concomitant activation of Lyn. The activation was accompanied by dephosphorylation of Lyn at its C-terminal negative regulatory tyrosine in cooperation with a protein tyrosine phosphatase. We propose that Chk but not Csk functions as a translocation-controlled negative regulator of CD36-anchored Lyn in thrombin-induced platelet activation.To further examine die role of Chk in hematopoietic cells, we overexpressed Chk in the megakaryocytic cell line Dami. Overexpression of Chk suppressed VLA5 integrin-mediated cell spreading, but not cell attachment, throughout fibronectin stimulation. This suppression was dependent upon both the SH3 domain, which is responsible for membrane anchoring, and kinase activity. Sustained activation of Lyn, which is regulated by membrane-anchored Chk, was required for VLA5-mediated cell spreading on a fibronectin substrate.Thus, these results suggest that Chk, unlike Csk, negatively regulates Src family kinases in vivo with selectivity toward Lyn and acts as a fine regulator in hematopoietic cells. Less

Src家族蛋白酪氨酸激酶在调节包括造血细胞在内的多种细胞类型的增殖和分化中起着至关重要的作用。Src家族激酶的活性受到酪氨酸磷酸化和去磷酸化事件的严格调节。广泛表达的C-末端Src激酶（Csk）已显示磷酸化Src家族激酶的C-末端负调节酪氨酸残基并抑制其激酶活性。Csk家族的第二个成员在造血细胞中表达，最近被确定为Csk同源激酶（Chk）。为了了解Chk和Csk在造血细胞中共表达的意义，我们检查了每个蛋白的亚细胞定位。Chk而不是Csk被定位在接近于CD 36（膜糖蛋白IV）锚定的林恩，并且林恩的激酶活性被选择性抑制。在凝血酶刺激下，Chk从CD 36锚定的林恩细胞上快速而完全的移位， ...更多信息同时激活了林恩。该活化伴随着林恩在其C-末端负调节酪氨酸与蛋白酪氨酸磷酸酶合作的去磷酸化。我们认为Chk而不是Csk在凝血酶诱导的血小板活化中作为CD 36锚定的林恩的易位控制负调节剂发挥作用。在整个纤连蛋白刺激过程中，Chk的过表达抑制VLA 5整合素介导的细胞扩散，但不抑制细胞附着。这种抑制依赖于负责膜锚定的SH 3结构域和激酶活性。持续激活的林恩，这是由膜锚定的Chk调节，需要VLA 5介导的细胞在纤连蛋白substrate. Therefore，这些结果表明，Chk，不像Csk，负调控Src家族激酶在体内选择性朝向林恩，并作为一个精细的调节造血细胞。少